From the Guidelines
Colistin is the preferred treatment option for multidrug-resistant (MDR) Acinetobacter infections, due to its better clinical efficacy compared to tigecycline, as recommended by the most recent guidelines 1. When treating MDR Acinetobacter infections, the choice of antibiotic is crucial for improving patient outcomes.
- Colistin (polymyxin E) is typically dosed at a loading dose of 5 mg CBA/kg IV, followed by 2.5 mg CBA IV every 12 hours, with adjustments needed for renal impairment 1.
- Tigecycline is dosed at 100 mg IV loading dose, followed by 50 mg IV every 12 hours, but its use as monotherapy is not recommended for pneumonia due to suboptimal serum and pulmonary concentrations 1. Key considerations for choosing between colistin and tigecycline include:
- Infection site: colistin is preferred for pneumonia and bloodstream infections due to its better clinical efficacy 1.
- Patient factors: tigecycline may be preferred in patients with renal impairment or those who cannot tolerate colistin's side effects, such as nephrotoxicity and neurotoxicity 1.
- Local resistance patterns and minimum inhibitory concentration (MIC) testing should also guide the choice of antibiotic 1. Combination therapy, such as colistin plus tigecycline or either drug plus a carbapenem, may be considered for severe infections to improve efficacy and reduce resistance development, although no significant statistical difference in clinical outcomes has been found between these alternative regimens 1.
From the Research
Comparison of Tigecycline and Colistin for MDR Acinetobacter Infections
- The study 2 compared tigecycline and colistin monotherapy and combination therapy against multidrug-resistant Acinetobacter baumannii (MDR-AB) using an in vitro pharmacodynamic model.
- The results showed that the combination of colistin plus tigecycline achieved a greater reduction in bacterial density than colistin alone, and both combinations significantly reduced the area under the bactericidal curve (AUBC) compared with colistin alone.
- Another study 3 found that the efficacy of tigecycline-based regimens was similar to other antibiotics, but with a higher mortality rate and lower rate of microbiological eradication compared to colistin-based regimens.
- A systematic review 4 found that combination treatment, including tigecycline with colistin, was superior to monotherapy in some studies, but the benefit was not validated in all studies.
- A case report 5 described the successful treatment of multidrug-resistant Acinetobacter baumannii ventriculitis with intrathecal and intravenous colistin, after initial treatment with a combination of intravenous colistin and tigecycline failed.
- A study 6 investigated the in vivo activity of daptomycin/colistin combination therapy in a Galleria mellonella model of Acinetobacter baumannii infection, but did not directly compare tigecycline and colistin.
Key Findings
- Combination therapy with tigecycline and colistin may be an effective treatment option for MDR Acinetobacter infections 2, 4.
- Colistin-based regimens may have a higher rate of microbiological eradication and lower mortality rate compared to tigecycline-based regimens 3.
- The efficacy of tigecycline and colistin combination therapy may depend on the specific strain of Acinetobacter baumannii and the patient's condition 2, 5.